Control device for internal combustion engines



Filed Nov 1, 1955 July 21,1959 r v A. BRUEDER 2,895,450

CONTROL DEVICE FOR INTERNAL COMBUSTION-ENGINES 2 Sheets-Sheet 1 A. BRUE'DER 2,895,460

July z1,' 1959 CONTROL DEVICE FOR INTERNAL comsusnon ENGINES Filed Nov. 1, 1955 2 Sheets-Sheet 2 Illllll 1 E I I i I I i g United States Patent CONTROL DEVICE FOR COMBUSTION ENGINES Antoine Brueder, Paris,

Anonyme Andre corporation France, assignor to Societe Citroen, Paris, France, a French The invention relates to the control devices of internal combustion engines for motor vehicles and, more particularly, to controls for such engines by which the power output is related to positionsof a control device such as an accelerator handle or pedalf It has hitherto been customary to control such engines by means of a pedal acting directly on the gas inlet throttle valve of the engine, so that, corresponding to one position of the accelerator, one and only one single position of the throttle which results in various power outputs depending on the angular speed of the engine, that is to say depending on the force of resistance to rotation of the engine moving parts. It may be advantageous to obtain a control device in accordance with which one given value, and only one, of the power of the engine corresponds to each position of the accelerator pedal, and the object of the present invention is to provide an engine control device for this purpose.

According to the invention a control device for an internal combustion engine comprises a solid body which having a surface representing the family of the curves each measuring the opening of the throttle valve (or some other member regulating the quantity or the richness of the combustible mixture delivered to the engine) dependent on the engine speed for a constant power output, this body being movable under the action of the speed in a predetermined direction and under the action of the displacement of the accelerator pedal in a perpendicular direction thereto, a feeler normal to the plane defined by these two directions remaining continually in contact with the aforesaid surface to act on the throttle opening mechanism or on any other suitable member for regulating the power output.

In order that the invention may be more clearly understood, one construction in accordance therewith will now be described by way of example with reference to the accompanying drawings, in which:

Fig. 1 is a schematic diagram with trirectangular coordinates;

Fig. 2 is a diagrammatic perspective view of an engine control device, and

Figs. 3 to 8 show operating diagrams.

In the system of coordinates with three rectangular axes o-x, ay, 0-z shown in Figure 1, 0x bears the values N of the angular speed of the engine, 0--y bears both the positions of the accelerator pedal defined by the stroke L and the values P of the power by making the values (power at idling) P and P (max. power of the engine) correspond respectively with L and L of two different positions of the accelerator pedal (for example L position of rest, L accelerator completely depressed); o-z bears the values Q of the throttle opening, measured for example from the angular value of rotation of the throttle valve about its axis.

Now, to any point In in the plane x-o-y determined by a power P and an engine speed N (and to which there likewise corresponds one and only one position of the accelerator L) there corresponds practically only one point M of the space measuring'the opening'of the throttle (in actual fact there exists one single position of the throttle opening which, for a determined speed Ii of the engine, enables a predetermined power P to, be obtained). i

The locus of the points M in the space is a surface 5 complying with the following conditions:

The sections of S through planes parallel to .to-z give curves of equal power. i

The sections of S through planes parallel to x-0-y give curves of equal throttle opening. Q The sections of S through planes parallel to yo -z give curves of equal angularspeed of the engine. i In the carrying into effect of the inventionyfor example for the embodiment shown 'in'Fig. 2,"the surface S is materialized, thus giving a certain volume with the planes of reference; the body 1 reproducing this volume is capableof moving independent of the speed N, for example a centrifugal governor 2 acting on a cranked lever 3 articulated at 4 and acting on a rod 5 the end of which is fixed to the body 1.

Moreover, the body 1 receives the movements of the accelerator pedal by means of a feeler 6 ensuring the displacement in the direction o-y, that is to say perpendicularly to the displacement produced by the speed, while a feeler 7 is applied to the surface S and controls the throttle opening valve or some other member acting on the quantity or richness of the combustible mixture delivered to the engine cylinders.

For the production of the body 1, the procedure may be as follows:

(1) After determining the device which is to ensure the displacement of the solid according to the engine speed, the curve is plotted of the displacement of the body 1 in dependence on the engine speed. A curve according to Figure 3 is thus obtained.

The displacement corresponding to the maximum speed gives one of the eifective dimensions of the body 1 (ON in Figure 1).

(2) The curve showing the displacement of the body 1 in dependence on the displacement of the pedal is deter mined, depending on the linkage system adopted. A curve such as that shown in Figure 4 is obtained.

The displacement of the body 1 corresponding to the position completely down of the pedal gives a second effective dimension of the body 1 (OL in Figure 1).

(3) The curve of power desired in dependence on the position of the pedal is plotted (Figure 5 (4) 'In dependence on the linkage adopted, the curve of throttle opening in dependence on the feeler 7 is determined, thus giving a curve as shown in Figure 6. The displacement corresponding to the maximum opening of the throttle gives a third dimension of the body 1 (O-Q Figure 1). a

(5) The network of the constant power curves in dependence on the opening of the throttle, and on the speed of the engine is then plotted for the engine in question (Figure 7).

Having all these elements, the outline of the body 1 no longer presents any difficulty. Let Figure 8 be the base reference plane for the body 1:

The values ON and O-L are known from the curves (Figures 3 and 4) and the obtaining of the dimension of any point m is obtained as follows:

m corresponds to a displacement D along Ox, thus to a speed N of the engine (Figure 3).

in also corresponds to a displacement D" on 0y, thus to a power P (Figure 5) When P and N are known, Figure 7 enables the opening Q of the throttle to be determined.

Figure 6 gi'ves,'fro'm the opening Q of the throttle, the displacement D" of the feeler 7. This value D will be the dimension of the point In fromv the plane of reference this plane corresponding to the opening Q of the throttle.

It will be seen that if L'does-not vary, the accelerator remaining unmoved, the speed of rotation acts on the throttle opening to keep the power constant. 7

It would also be possible to imagine a device of the same kind but in which the surface S would be traced in polar coordinates;

I claim:

1. A control mechanism forlvarying the power output I A of an engine for a motor vehicle and maintaining constant the power output for a determined position of the control mechanism in response to an accelerator foot pedal comprising a throttle for controlling air fuel'mixture, a

cam defining a three-dimensional active cam surface, first linkage means coupling said cam to said foot pedal for controlling a first unidirectional movement of said cam, indicating means fo r'iindicating the speedof said engine, second linkage means couplingsaid indicating means to said cam for controlling a second unidirectional movement of said cam to compensate for speed variations of said engine, and a feeler supported on said surface and coupled to said throttle for the exclusive control thereof in response to the position of said cam and thereby in response both to the position of said foot pedal and said indicating means, the active surface of the cam representing a family of curves each corresponding to the opening of the throttle valve dependent on the engine speed for a constant power output. V

2. A mechanism as claimed in claim 1 wherein the cam has a first planar surface on which the cam is slidable, and a second'planar surface perpendicular to the first planar surface and engaged by the first linkage.

References Cited in the file'of this patent V UNITED STATES PATENTS 2,193,927 Jivkovitch Mar. 19, 1940 2,473,171 Ostling June 14, 1949 v p H FOREIGN PATENTS 459,007 France Aug. 22, 1913 949,791 France Feb. 28, 1949 962,124

France Dec. 5, 1949 

